R1:4b94ae15e0bc

Straighten out some stacked action removal behaviors

Summary: Fixes T12065. Some of the normal behavior of these actions got juggled when I made "Accept" and "Reject" conflict.

Test Plan:
- Added "Accept".
- Added "Reject", saw it remove "Accept".
- Added "Change Projects".
- Added "Assign/Claim".
- Removed "Assign/Claim".
- Removed "Accept".

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12065

Differential Revision: https://secure.phabricator.com/D17143